1. Field of the Invention
The present invention relates to antigen proteins of Mycoplasma gallisepticum that are infections to poultry, genes encoding the antigen proteins, recombinant vectors integrated with the genes encoding the antigen proteins, hosts transformed by the vectors, as well as poultry diagnostics and vaccines for Mycoplasma gallisepticum infections utilizing the antigen proteins produced by the hosts.
2. Discussion of Prior Art
Mycoplasma gallisepticum infectious disease that is one of the most serious infections on poultry such as chickens, is characterized by chronic respiratory disturbance accompanied by inflammation of the air sac in a chicken. A chicken infected with Mycoplasma gallisepticum as a pathogen develops very slight symptoms and rarely comes to death. However, when infected with Mycoplasma gallisepticum, an egg-laying rate and a hatching rate of eggs produced by infected chickens are markedly reduced. As a result, shipping of eggs and egg-laying chickens are decreased, resulting in considerable economic loss. In addition, Mycoplasma gallisepticum infection induces the reduction in immunity so that chickens are liable to suffer from other infectious diseases and to cause complication of severe infectious diseases. Furthermore, Mycoplasma gallisepticum is known to be a pathogen of infectious paranasal sinusitis in turkeys.
Efforts have been hitherto made to prevent poultry Mycoplasma gallisepticum infections using antibiotics or by vaccination and to establish pathogen-free poultry. However, administration of antibiotics involves defects that bacilli resistant to Mycoplasma would appear and Mycoplasma would readily proliferate after discontinuation of administration of antibiotics. On the other hand, prophylaxis by vaccination using attenuated Mycoplasma might cause opportunistic infections with other pathogens, or Mycoplasma gallisepticum infections. As stated above, it is highly difficult to establish and maintain a group of poultry free of infections with Mycoplasma.
Turning to a determination of whether or not poultry is infected with Mycoplasma gallisepticum, it has been judged by determining if serum collected from poultry could inhibit proliferation of Mycoplasma to form a characteristic inhibition zone on PPLO agar plate including glucose and donor horse serum. However, the method involves shortcomings that 3 to 7 days are required to judge whether or not a clear inhibition zone is formed; during the period, infection tends to be spread over the whole group of poultry.
As a result of extensive investigations to solve the drawbacks in the prior art, the present inventors have discovered polypeptides derived from Mycoplasma gallisepticum and having antigenicity of Mycoplasma gallisepticum and further found that antisera, derived from the polypeptides using said polypeptides as antigens, can prevent growth of Mycoplasma gallisepticum and, the polypeptides are expected to be useful as poultry vaccines capable of preventing Mycoplasma gallisepticum infections and are useful as poultry diagnostics for Mycoplasma gallisepticum infections. The present invention has thus come to be accomplished.